A. Field of the Invention
The invention relates generally to the production of oxygenated hydrocarbons such as lower alcohols and preferably 1,2-propanediol. More particularly, this invention comprises a single-step catalytic process for the catalytic production of lower alcohols such as methanol, ethanol, propanol, ethylene glycol and 1,2-propanediol from glycerol. This invention relates to valorizing glycerol, which is a byproduct from saponification and transesterification processes, e.g. for the production of biodiesel, into value-added chemicals. The catalyst comprises a metal selected from the Group VIII transition metals, preferably platinum, alloys thereof and mixtures thereof deposited on a porous carrier, preferably a microporous carrier, and more preferably a faujasite Y-type zeolite.
Several documents are cited throughout the text of this specification. Each of the documents herein (including any manufacturer's specifications, instructions etc.) are hereby incorporated by reference; however, there is no admission that any document cited is indeed prior art of the present invention.
B. Description of the Related Art
Previous disclosures in the art for the one-pot conversion of glycerol to 1,2-propanediol describe the use both homogeneous and heterogeneous catalytic systems The application of pressures of a second reagent such as H2.
Patent WO9905085 by Wabe et al. describes the reaction of 10 wt % glycerol with a homogeneous catalyst composed of an organic Pd-complex in the presence of sulpholane and water at 140° C. and a pressure of 5.2 MPa synthesis gas (syngas (H2/CO)) for 19 h. The conversion of glycerol in a continuous reactor is 13 mol/mol.h with a 1,2-propanediol selectivity of 22%. These inventors also tested Pd and Ru catalyst on carbon and a Rh-complex.
U.S. Pat. No. 4,642,394 by Che et al. describes the reaction of 30 wt % glycerol in presence of a homogeneous catalyst, Rh(CO)2acac with H2WO4, in 1-methyl-2-pyrrolidinone as a solvent. The reaction is carried out at a temperature of 200° C. with a pressure of 31.7 MPa syngas .(H2/CO) for 24 h. The reaction yielded 19% 1,2-propanediol and 18% 1,3-propanediol at a conversion of 39% and selectivities of 49 and 45%, respectively. In this document the testing of catalysts composed of Fe, Co, Ni, Ru, Pd, Os or Pt and other aprotic organic solvents, was also described.
Gallezot et al. published in Green Chemistry 6 (2004) the reaction for 168 h of 20 wt % aqueous solution of glycerol with 8 MPa of H2 and CuO/ZnO as a heterogeneous catalyst at a temperature of 180° C. At a conversion of 19% they obtain a selectivity for 1,2-propanediol of 100%. Pd/C, Rh/Al2O3, Rh/Nafion, Rh/HY as catalysts, water, sulpholane and dioxane as solvents and Fe-, Ni-, Mn-, Cu-salts and HCl as additives, were claimed as well.
In Catalysis Communications 6, 645-649 (2005) Kusunoki et al. describe the reaction for 40 h of 20 wt % aqueous solution of glycerol with 4 MPa of H2 and Ru/C with Amberlyst 15 as a heterogeneous catalyst at a temperature of 120° C. At a conversion of 33% a 1,2-propanediol selectivity of 60% was obtained, yielding 20% of 1,2-propanediol. Pt/C, Pd/C, Rh/C with homogeneous or heterogeneous acids (SO42−/ZrO2, BEA, USY, MFI, H2WO4) were also claimed as catalysts.
Dasari et al., Applied Catalysis A: General 281, 225 (2005), obtained high yields of 1,2-propanediol after 24 h in moderate conditions with CuCr as an heterogeneous catalyst at a temperature of 200° C. and a pressure of 1.4 MPa of H2. At a conversion of 69% a selectivity for 1,2-propanediol of 72% was obtained. Ru/C, Ru/alumina, Pd/C, Pt/C, Raney nickel, Raney copper, Cu, Ni/C and Ni/silica-alumina were also used as heterogeneous catalysts.
In WO 2005/095536 A2, the conversion of glycerol to 1,2-propanediol with high selectivity is described. The reaction proceeds at 200° C. for 24 h in a closed reactor, pressurized with 1.4 MPa of H2. A prereduced commercial copper chromium converts 86% of a 57 wt % crude glycerol feedstock to 1,2-propanediol with a selectivity of 80%.
In EU Patent 1 440 046 (2004), 25 wt % glycerol in water is converted within 4 h at a temperature of 230° C. under a H2-pressure of 12.4 MPa, using a ReNi multimetallic heterogeneous catalyst with NaOH as a homogeneous additive, to yield 54% of 1,2-propanediol with a conversion of 61% and a selectivity of 88%.
Schuster et al. describe in U.S. Pat. No. 5,616,817 (1997) the full conversion of glycerol to yield 96% of 1,2-propanediol in severe process conditions. The heterogeneous catalyst comprises a mixed oxide of Co, Cu, Mn and Mo and H3PO4 as homogeneous additive. The reactions are carried out for 6 h at 230° C. and a hydrogen pressure of 25 MPa.
In U.S. Pat. No. 5,276,181 (1994), Casale et al. obtain 1,2-propanediol yields of 75% in severe process conditions. All glycerol form a 30 wt % aqueous solution is converted at 240° C. for 2 h under 13 MPa of hydrogen, using RuS/C as a heterogeneous catalyst and addition of NaOH.
Casale et al., U.S. Pat. No. 5,214,219, 1993), were using CuZn-oxide/Al2O3 as a heterogeneous catalyst. After 2 h at 270° C. and with a hydrogen pressure of 10 MPa, a 30 wt % aqueous glycerol solution is almost fully converted, with a 1,2-propanediol selectivity of 84%.
Montassier et al. (Journal of Molecular Catalysis, 70 (1), 99 (1991)) reported the conversion of diluted aqueous glycerol into 1,2-propanediol at 210° C. and a hydrogen pressure of 6 MPa, with a heterogeneous Ru/C. At full conversion, a yield of 75% of 1,2-propanediol was obtained.
Montassier et al., also reported (Heterogeneous Catalysis and Fine Chemicals, Studies in Surface Science and Catalysis, 41, 165 (1988)) a method for producing 1,2-propanediol from a 1 to 4 wt % aqueous solutions of glycerol. Raney Cu was used as heterogeneous catalyst in a reaction at 240° C. for 6 and a hydrogen pressure of 3 MPa 1,2-Propanediol yields of 57% were obtained with conversions of 86% and selectivities of 66%). Cu, Co, Pt, Ru, Rh and Ir/silica, Raney Co and Raney Ni catalysts were claimed as well.